1. Field of the Invention
The present invention relates to keyboard instruments, and more particularly, to automatic playing keyboard instruments and devices for assessing characteristics of a performer's operation of keys on the keyboard of such an instrument.
2. Prior Art
Automatic playing keyboard instruments such as automatic playing (player) pianos conventionally incorporate means for quantifying the force with which keys are depressed and other characteristics of a performance, in this way making it possible to record data expressing various aspects of a performance on the instrument which can be later reproduced so as to provide for automatic playback which faithfully duplicates the original performance.
With conventional automatic playing pianos, each key on the keyboard has a corresponding dedicated hammer mechanism just as is the case with an ordinary manual piano. With the automatic playing instrument, each hammer mechanism further includes a shutter which moves in concert with the corresponding hammer, and a pair of photocells which are situated such that movement of the hammer and hence the shutter results in momentary occlusion of light incident on one of the photocells, and then occlusion light incident on the other, in this way making it possible to measure the velocity with which a key is depressed.
With conventional means for measuring the velocity with which a hammer mechanism moves, however, because only a single distance interval is measured, only a simple averaged value of the hammer velocity is obtained. As a result, the finer nuances of a performance cannot be readily assessed for which reason the fidelity of reproduction on automatic playback suffers.
Furthermore, because the measured time interval is short, the orientation of the photocells and shutter incorporated into each hammer mechanism is quite critical. For this reason, assembly and calibration for all eighty-eight keys on a conventional keyboard is cumbersome and time consuming, with the result that these conventional instruments tend to be expensive. Additionally, this type of mechanism is prone to loss of alignment with time, resulting in increased maintenance requirements and expenses.